Data from: Hormonal and metabolic responses to upper temperature extremes in divergent life-history ecotypes of a garter snake

Extreme temperatures constrain organismal physiology and impose both acute and chronic effects. Additionally, temperature-induced hormone-mediated stress response pathways and energetic trade-offs are important drivers of life-history variation. This study employs an integrative approach to quantify acute physiological responses to high temperatures in divergent life-history ecotypes of the western terrestrial garter snake (Thamnophis elegans). Using wild-caught animals, we measured oxygen consumption rate and physiological markers of hormonal stress response, energy availability, and anaerobic respiration in blood plasma across five ecologically relevant temperatures (24, 28, 32, 35, and 38° C; 3-hour exposure). Corticosterone, insulin, and glucose concentrations all increased with temperature, but with different thermal response curves, suggesting that high temperatures differently affect energy-regulation pathways. Additionally, oxygen consumption rate increased without plateau and lactate concentration did not increase with temperature, challenging the recent hypothesis that oxygen limitation sets upper thermal tolerance limits. Finally, animals had similar physiological thermal responses to high-temperature exposure regardless of genetic background, suggesting that local adaptation has not resulted in fixed differences between ecotypes. Together, these results identify some of the mechanisms by which higher temperatures alter hormonal-mediated energy balance in reptiles and potential limits to the flexibility of this response.

极端高温会约束生物体的生理机能，并带来急性与慢性双重影响。此外，温度诱导的激素介导应激反应通路与能量权衡，是驱动生物生活史变异的重要因素。本研究采用整合研究方法，对西部陆栖束带蛇（Thamnophis elegans）不同生活史生态型个体的高温急性生理响应进行量化分析。本研究使用野外捕获的个体，在5个符合生态相关性的温度梯度（24、28、32、35、38℃；暴露3小时）下，测定了其血浆中的耗氧率，以及激素应激反应、能量可用性与无氧呼吸相关的生理标志物水平。皮质酮、胰岛素与葡萄糖浓度均随温度升高而上升，但呈现出不同的温度响应曲线，这表明高温对能量调控通路的影响存在差异。此外，耗氧率持续上升未出现平台期，而乳酸浓度未随温度升高而增加，这对近期提出的“氧气限制决定热耐受上限”假说提出了挑战。最后，无论遗传背景如何，受试个体在高温暴露下的生理热响应均无显著差异，这表明局部适应并未导致不同生态型之间出现固定的生理差异。综上，本研究结果阐明了高温改变爬行动物激素介导能量平衡的部分机制，以及该响应灵活性的潜在限制因素。